Field
The present disclosure relates to a motor drive apparatus, a method of controlling a motor drive apparatus, and an electrically powered vehicle, and more particularly to a motor drive apparatus including a converter between a power storage device and an inverter, a method of controlling the motor drive apparatus, and an electrically powered vehicle including a converter between a power storage device and an inverter.
Description of the Background Art
The vehicle disclosed in Japanese Patent Laying-Open No. 2009-60726 includes a battery, an inverter, a boost converter provided between the battery and the inverter, and a smoothing capacitor for smoothing voltage of the inverter. The boost converter includes an upper anti and a lower arm. Each of the upper arm and the lower arm includes an IGBT (Insulated Gate Bipolar Transistor) element and a diode connected in anti-parallel with the IGBT element.
This vehicle further includes an overvoltage protection circuit that limits the operation of the boost converter when the voltage of the smoothing capacitor exceeds an overvoltage threshold. In this vehicle, when an abnormality occurs in the overvoltage protection circuit, upper arm ON running is performed. The upper arm ON running refers to running performed in a state in which the upper IGBT element is fixed ON and the lower IGBT element is fixed OFF (upper arm ON state). During upper arm ON running, voltage boost by the boost converter is not performed. This vehicle, therefore, is able to run while preventing overvoltage of the smoothing capacitor when an abnormality occurs in the overvoltage protection circuit.
This vehicle runs in a state in which the boost converter is shut down when an abnormality occurs in the boost converter. In this case, since the boost converter is shut down, boosting voltage by the boost converter is not performed. In this vehicle, therefore, overvoltage of the smoothing capacitor can be prevented also when an abnormality occurs in the boost converter.
In the vehicle disclosed in Japanese Patent Laying-Open No. 2009-60726, since the boost converter is shut down during running in a state in which the boost converter has an abnormality, power supply from the battery to the inverter is performed, whereas power supply from the inverter to the battery is not performed. Accordingly, electricity is merely discharged from the battery during running, so that running can continue only for a short distance determined by the amount of charge of the battery.
Meanwhile, when the abnormality in the boost converter is a short circuit in the (upper) IGBT element (switching element) included in the upper arm, the upper arm ON running can be performed. In the upper arm ON running, electric power generated by the motor connected to the inverter can be supplied to the battery, thereby increasing the distance of travel.
The inventors of the present disclosure, however, have found that the converter generates a fail signal when an ON signal is input to the short-circuited switching element in order to perform the upper arm ON running. Suppose that in a system in which the converter generates a fail signal when the switching element is short-circuited, when a fail signal is generated by the converter, an ON signal is input to the short-circuited upper switching element in order to perform the upper arm ON running. In such a system, during short-circuiting of the upper switching element, generation of a fail signal associated with input of an ON signal to the upper switching element and input of an ON signal to the upper switching element associated with generation of a fail signal are repeated, and the upper arm ON running fails to be performed.